IxSet中的文本索引

Question

似乎我不明白IxSet的文本索引应该如何工作。在这里，我创建了一个单元测试，它按tags字段索引项目，然后按标记"tag"查询项目。它应该(从我的角度来看)把我所有的3件物品都还给我(因为它们都有标签"标签")，但似乎他们没有。我不明白为什么。

{-# LANGUAGE DeriveDataTypeable #-}
import Test.HUnit
import Data.IxSet
import Data.List.Split ( splitOn )
import Data.Data ( Data, Typeable )
data TaggedItem = TaggedItem { getTags :: String }
                  deriving ( Show, Ord, Eq, Data, Typeable )
data Tag = Tag String
           deriving ( Show, Ord, Eq, Data, Typeable )
getTagStrings :: TaggedItem -> [Tag]
getTagStrings = map Tag . splitOn "," . getTags
instance Indexable TaggedItem where
  empty = ixSet
            [ ixFun getTagStrings ]
test3 = TestCase (
  assertEqual "ixFun multiple tags test"
  3
  (size (index @= (Tag "tag"))) )
  where items = [ TaggedItem "tag,tag1,tag2"
                , TaggedItem "tag,tag1,tag2"
                , TaggedItem "tag,tag1,tag2" ]
        index = fromList items
tests = TestList [
  -- TestLabel "test1" test1,
  -- TestLabel "test2" test2,
  TestLabel "test3" test3]
main = do
  runTestTT tests

更新:

嗯，很有趣。我添加了字段"name"，并使每个项目的名称不同，现在它可以工作了。

{-# LANGUAGE DeriveDataTypeable #-}
import Test.HUnit
import Data.IxSet
import Data.List.Split ( splitOn )
import Data.Data ( Data, Typeable )
newtype TaggedItemName = TaggedItemName { unTaggedItemName :: String }
                       deriving ( Show, Ord, Eq, Data, Typeable )
data TaggedItem = TaggedItem { getName :: TaggedItemName, getTags :: String }
                deriving ( Show, Ord, Eq, Data, Typeable )
data Tag = Tag String
           deriving ( Show, Ord, Eq, Data, Typeable )
getTagStrings :: TaggedItem -> [Tag]
getTagStrings = map Tag . splitOn "," . getTags
instance Indexable TaggedItem where
  empty = ixSet
            [ ixFun getTagStrings ]
test3 = TestCase (
  assertEqual "ixFun multiple tags test"
  3
  (size (index @= (Tag "tag"))) )
  where items = [ TaggedItem (TaggedItemName "name1") "tag,tag1,tag2"
                , TaggedItem (TaggedItemName "name2") "tag,tag1,tag2"
                , TaggedItem (TaggedItemName "name3") "tag,tag1,tag2" ]
        index = fromList items
tests = TestList [
  -- TestLabel "test1" test1,
  -- TestLabel "test2" test2,
  TestLabel "test3" test3]
main = do
  runTestTT tests

。因此，IxSet可能认为这些项是相同的，并以某种方式合并它们(?)

Answer 1

是的，IxSet似乎合并了相等的值。我以第一个例子为例，并将其更改为:

  where items = [ TaggedItem "tag,tag1,tag2"
                , TaggedItem "tag,tag3,tag4"
                , TaggedItem "tag,tag5,tag6" ]

现在也可以了